S. Afr. J. mar. Sci. 18: 305Ð308 1997 305

A NEW RECORD OF THE ECHIURAN (PALLAS, 1767) FROM THE EAST COAST OF SOUTHERN AFRICA

R. BISESWAR*

The Echiurus echiurus (Pallas, 1767) of the family Echiuridae, originally described from shallow waters of the Belgian coast, was later recorded from many other localities in the northern hemisphere, pre- dominantly in cold waters and extending even into the Arctic. The discovery of this species from the warm, subtropical waters of the east coast of southern Africa is the first record of its occurrence in the southern hemisphere and marks a considerable extension of its geographic range. The species is briefly redescribed and some of the taxonomic characters have been reviewed.

According to the system of classification adopted by coast, off Tugela Bluff; collected 15 June 1989 at Stephen and Edmonds (1972), the phylum 29¡25.9′ S Ð 31¡43.6′ E from 70 m depth. contains four families, 34 genera and 129 species. However, since the publication of their monograph, several new species have been added to the list. Description colour According to Popkov (1992), approximately 145 species have been described. White in preserved specimen. Knowledge of the echiuran fauna of southern Africa is limited; only 20 species belonging to five genera are currently known from that subcontinent. External features Some of the earlier and more significant works on this group in southern Africa are those of Wesenberg- Proboscis Ð Missing. Lund (1959, 1963) and Stephen and Cutler (1969). Biseswar (1985) provided a checklist of all the genera Trunk Ð Cylindrical or sausage-shaped (Fig. 1), 25 mm and species from southern Africa and mapped their long, widest diameter 11 mm. Body wall thin and distribution. Since 1984, several new species or new transparent throughout, with the result that internal records have come to light (Biseswar 1984, 1988a, organs and contents of gut are visible. Outer layer of b). Although most of the species have been found in integument in posterior half of trunk separated from shallow waters of the intertidal zone, a few have been inner layers but still attached to trunk. Papillae conical, reported from considerable depths. Investigations projecting from surface of integument, arranged in into the deeper continental shelf and abyssal fauna concentric rings around trunk. With the unaided eye, should reveal new species or new records. papillae appear as spherical, transparent spots. Rows This study reports on the first record of the occur- of larger papillae alternate with three or four rows of rence of Echiurus echiurus from the subtropical waters uniform smaller papillae. of the east coast of southern Africa. The species is diagnosed and briefly redescribed. Setae Ð One pair of ventral setae (Fig. 2), golden- brown in colour, located about 5 mm from the anterior tip of trunk. Each seta is about 3.5 mm long, consisting DESCRIPTION of a more or less cylindrical shaft with a hook-like terminal blade. Curved terminal part flattened with ECHIURUS ECHIURUS faint concentric markings. Internally, setae located in (PALLAS 1767) setal sacs, supported by thin radiating muscle strands. A narrow interbasal muscle present between the Material setae (Fig. 3). Two rows of prominent anal setae around posterior end of trunk (Fig. 1). Eight setae in One sexually mature male specimen; Natal north the anterior row and six in the posterior row.

* Department of Zoology, University of Durban-Westville, Private Bag X54001, Durban 4000, South Africa. E-mail:[email protected] Manuscript received: December 1996 306 South African Journal of Marine Science 18 1997

Fig. 2: Ventral seta of Echiurus echiurus

with spermatozoa and exceeding more than half the length of the trunk. Gonostomes small, funnel-like, opening into base of gonoduct. Blood system Ð Only ventral vessel and intestinal Fig. 1: Lateral view of Echiurus echiurus ring sinus visible. Dorsal and neuro-intestinal vessels damaged as a result of poor preservation. Internal anatomy Anal vesicles Ð Anal vesicles absent, probably dam- Alimentary canal Ð Alimentary canal long and aged because posterior part of alimentary canal frag- coiled, attached to body wall by few, thin and delicate mented in several places. mesenteric strands. Foregut short, more or less a straight tube, leading from pharynx and forming a loop at posterior end (Fig. 3). Intestinal ring vessel located at DISCUSSION terminal end of foregut just after the loop (Fig. 3). Remainder of intestine thin-walled, transparent with sausage-shaped faecal pellets. Rectal caecum absent. The subfamily Echiurinae is distinguished in having two rings of anal setae around the posterior end of the Gonoducts Ð Two pairs of gonoducts (Fig. 4), tubu- trunk. It is represented by a single , Echiurus, lar, considerably distended at terminal end and post- in which the proboscis is well developed but often setal in position. All four gonoducts compactly filled deciduous. The papillae are arranged in rows over 1997 Biseswar: New Record of Echiurus echiurus from South Africa 307

Fig. 3: Anterior end of trunk cavity of Echiurus echiurus, showing the internal organs; interbasal muscle (ibm), intestine (int), intestinal ring sinus (irs), nerve Fig. 4: Gonoduct (gd) of Echiurus echiurus, showing the cord (nc), oesophagus (oes), pharynx (ph), setal basal gonostome (gs) sac (ss), ventral seta (vs), ventral vessel (vv)

The characteristic arrangement of the dermal the surface of the trunk. Other distinguishing features papillae in ring rows, the presence of two pairs of of the genus are the presence of one to three pairs of postsetal gonoducts and the structure of the gono- gonoducts with gonostomes that are not elongate and stomes are almost identical to the descriptions provided spirally coiled. A post-pharyngeal diaphragm is present by Greeff (1879), Spengel (1880) and Stephen and which almost divides the coelom into two parts. An Edmonds (1972). The number of anal setae appears intestinal ring sinus connects the dorsal and neuro- to be variable in E. echiurus. According to Stephen intestinal vessels. Unlike the bonellids, there is no and Edmonds (1972), there are five to nine (usually sexual dimorphism. seven) setae in the anterior row and five to eight The genus Echiurus is currently represented by four (usually six) setae in the posterior row. species. Stephen and Edmonds (1972) consider Echiurus Echiurus antarcticus Spengel, 1912 is another echiurus alaskanus Fisher, 1948 as a subspecies of species that has been recorded from southern Africa E. echiurus. The species E. echiurus was originally (Stephen and Cutler 1969). Those specimens were described as Lumbricus echiurus by Pallas (1766) collected from the KwaZulu-Natal coast in the vicinity of (quoted from Stephen and Edmonds 1972). According Durban. Echiurus antarcticus differs from E. echiurus to Gislén (1940), the type specimens were found in in possessing three pairs of gonoducts and a proboscis shallow water along the coast of Belgium. Since its that is T-shaped. discovery from that coast, the species has been From the recorded localities given by Stephen and recorded from many other localities (Stephen and Edmonds (1972), E. echiurus is a northern species Edmonds 1972). The anatomy of E. echiurus is well that is found predominantly in cold waters and which known because it has been redescribed and illustrated extends even into the Arctic. The present discovery in considerable detail by Greeff (1879) and Spengel of this species from the warm, subtropical waters of (1880). The present specimen from the east coast of the east coast of southern Africa is a first record of southern Africa closely approaches the descriptions its occurrence in the southern hemisphere and marks given by those authors. a considerable extension of its geographic range. 308 South African Journal of Marine Science 18 1997

Additional records in the future may indicate that Africa with a description of a new species. Ann. S. Afr. this species has a bipolar distribution. Mus. 98(2): 29Ð75. BISESWAR, R. 1988b — Thalassema (Echiura) from southern Africa with the description of a new species. S. Afr. J. Zool. 23(2): 81Ð91. ACKNOWLEDGEMENTS GISLÉN, T. 1940 — Investigations on the ecology of Echiurus. Lunds Univ. Arsskrift N. F. 36(10): 1Ð39 + 6 Plates. GREEFF R. 1879 — Die Echiuren (Gephyrea armata). Nova Acta Leopoldina. 41(2): 1Ð172 + 9 Plates. I thank Drs R. Kilburn and D. Herbert of the Natal POPKOV, D. V. 1992 — A new echiuran species Thalassema Museum for the loan of the specimen. Financial support malakhovi (Echiura) from New Zealand. N. Z. Jl mar. from the University of Durban-Westville is gratefully Freshwat. Res. 26: 379Ð383. SPENGEL, J. W. 1880 — Beitrage zur Kenntnis der Gephyreen 11. acknowledged. Die Organisation des Echiurus pallasii. Z. wiss. Zool. 34: 460Ð534. STEPHEN, A. C. and E. B. CUTLER 1969 — On a collection of Sipuncula, Echiura and Priapulida from South African waters. LITERATURE CITED Trans. R. Soc. S. Afr. 38(2): 111Ð121. STEPHEN, A. C. and S. J. EDMONDS 1972 — The Phyla Sipuncula and Echiura. London; British Museum (Natural BISESWAR, R. 1984 — A key to the species of Anelassorhynchus History): 528 pp. (Echiura) with a description of a new species from the east WESENBERG-LUND, E. 1959 — Sipunculoidea and coast of southern Africa. S. Afr. J. Zool. 19(1): 16Ð21. from tropical West Africa. “Atlantide” Rep. 5: 177Ð210. BISESWAR, R. 1985 — The geographic distribution of Echiura WESENBERG-LUND, E. 1963 — South African sipunculids and from southern Africa. S. Afr. J. mar. Sci. 3: 11Ð21. echiuroids from coastal waters. Vidensk. Meddr dansk. BISESWAR, R. 1988a — Ochetostoma (Echiura) from southern naturh. Foren. 125: 101Ð146.